1. Field of the Invention
The invention relates to a filter module with several discoid filter cells stacked on top one another which each have a central opening through which at least one element receiving tensile forces extends which with its axial end is connected to closing rings of the filter module having at their end faces a flat packing.
2. Description of the Related Art
In U.S. Pat. No. 5,482,624 a filter module is described which is comprised of several stacked filter cells wherein each filter cell has a central opening. The filter cells are aligned such that the central openings are congruently placed above one another. At the upper and lower end a respective closing ring is arranged which supports a sealing ring so that the filter module can be connected sealingly to a connecting tube or another filter module. Tie rods in the form of strips of stainless steel extend through the central openings of all filter cells of a filter module and are connected respectively to the closing rings provided at the ends.
In DE 295 20 418 U1 a filter device for the treatment of liquids is described in which two filter modules are arranged above one another in a pressure container. These filter modules are comprised of several stacked discoid filter cells wherein at the respective axial end faces of the filter modules closing rings with seals are provided. For positioning the central channels within the interior of the filter modules centering means are provided which respectively engage in the ends of the closing rings of neighboring filter modules.
In DE 40 26 934 C2 a central support tube for the filter modules is described which is designed for receiving filter cells. At the respective ends of the central support tube adaptors are provided wherein one adaptor has a seal comprising two O-rings. The other adaptor forms an exact counter piece, i.e., it is configured to receive a further adaptor, for example, of the next filter module where again two O-rings are provided as a sealing arrangement. The adaptors are provided with a bayonet closure for a mechanically stable connection of the adaptors of two neighboring filter modules.
Moreover, filter modules with flat adaptors are known which have closing rings with flat packings. These modules can be stacked within a filter housing wherein in the filter housing a centrally arranged tube is provided in order to realize the required positional securing action for the arrangement. A compression device is provided at the upper end in order to provide a sufficient sealing action between the individual modules or the connectors at the ends of the arrangement.